While ROVs vary in design and capability, they can generally travel much deeper than manned vessels, Englot said. "Those kind of vehicles usually have robotic arms that are capable of carrying a payload, grasping an object, grabbing and turning a knob or a valve or something like that," he added. As of Thursday morning, several with the ability to reach the ocean floor had been deployed in the Atlantic as the Titan's estimated initial supply of 96 hours of oxygen dwindled – including the Victor 6000, which descended from the French L'Atalante research vessel to the ocean floor. File image of an asset of the rescue efforts – the Victor 6000 – an unmanned French robot which can dive up to 6,000 metres. It has arms that can be remotely controlled to cut cables or otherwise help release a stuck vessel. However, it does not have the capability of lifting the submersible on its own.

Fox News correspondent Molly Line has more on the search to rescue the five individuals on the Titanic voyage on'Special Report.' BOSTON – Three new vessels arrived "on-scene" in the Atlantic Ocean Wednesday morning to join search and rescue efforts for the missing OceanGate Titan sub as the estimated oxygen supply on board continues to dwindle. The U.S. Coast Guard said the new vessels bring additional tools to scan the ocean floor as they race against the clock to save the five people onboard: OceanGate CEO Stockton Rush, British businessman Hamish Harding, father-and-son Shahzada and Suleman Dawood, who are members of one of Pakistan's wealthiest families, and Paul-Henry Nargeolet, a former French navy officer and leading Titanic expert. "The John Cabot has side-scanning sonar capabilities and is conducting search patterns alongside the Skandi Vinland and the Atlantic Merlin," the Coast Guard said. The John Cabot is a Canadian coast guard vessel, the Atlantic Merlin is a Canadian remotely operated vehicle (ROV), and the Skandi Vinland is a commercial ROV, authorities said.